The objective of this application is to obtain support to fund travel expenses and board plus lodging fees for the invited speakers and discussion leaders at the Gordon Research Conference on Fertilization and the Activation of Development, to be held at Holderness School, Plymouth, NH, August 4-11, 1991. This conference has been held every two years since 1974. It is the only Gordon Conference concerned with the interactin of the male and the female gamete in the vital process of fertilization and activation of the fertilized egg to begin the process of embryo formation. It provides a venue for the interaction of biochemists, cell biologists, molecular biologists, physiologists, and biophysicists working in the field. All these disciplines and their interdisciplinary offspring are represented, due to the extraordinary complexity of the processes under study, and the large span of dimensions, from small molecules to whole sperm and egg, in which occur the reactions of gamete interaction. This conference has been singularly successful in fostering collaborations between workers in the middle and on the periphery of the field, between researchers of similar and widely disparate experience and seniority, and between research laboratories in this country and Japan, Europe, Australia, and Latin America. These collaborations have borne many fruitful results. There will be nine sessions in the conference, following the Gordon Conference format. 1): Sperm plasma membrane mosaics and movements. 2): Mechanisms of sperm egg fusion. 3.): Cell cycle in fertilization 1. 4): Cell cycle in fertilization 11. 5): Activation signalling in gametes I. 6.): Activation signalling in gametes II. 7.) Mouse genetic models in fertilization. 8): Genetics of gametes and fertilization in mouse. 9): Calcium movements in activated gametes. Session 8 is the plenary lecture, a particular tradition of this conference. It will be given by Dr. Halina Krzanowska of Jagellonian University, Krakow, Poland. Dr. Krzanowska has long been a leader in the application of genetics to questions of fertilization in the mouse model. Her participation will give the conferees the special opportunity to meet a world class investigator, whose ability to attend international meetings had been severely curbed in this decade.